private static void CorrectFishEye(ImageGrid grid, float correctionRadius, RgbColor[] buffer)
{
// calculate the coordinates of the center of the image
var centerX = grid.Width / 2;
var centerY = grid.Height / 2;
// iterate through all horizontal lines
for (var y = 0; y < grid.Height; y++)
{
// calculate the y-coordinate currently processing and precompute the squared value
// of the current center y-coordinate being processed
var currentY = y - centerY;
var currentYSquared = MathF.Pow(currentY, 2);
// iterate through all vertical lines in the current horizontal scan line
for (var x = 0; x < grid.Width; x++)
{
// calculate the x-coordinate currently processing and compute the squared value
// of the current center x-coordinate being processed
var currentX = x - centerX;
var currentXSquared = MathF.Pow(currentX, 2);
// compute the distance between the original center and the current point
var distance = MathF.Sqrt(currentXSquared + currentYSquared);
// compute the current correction radius to perform correction with
var radius = distance / correctionRadius;
// the theta used as a factor to correct the fish-eye distortion, pre-initialize
// with 1F to avoid division through zero errors
var theta = 1F;
// check if the radius is not zero, to avoid division through zero errors
if (radius is not 0.0F)
{
// compute the theta
theta = MathF.Atan(radius) / radius;
}
// calculate the coordinates of the pixel to retrieve the value from
var sourceX = (int)MathF.Floor(centerX + (theta * currentX));
var sourceY = (int)MathF.Floor(centerY + (theta * currentY));
// retrieve the value of the source pixel
var value = grid.GetPixel(sourceX, sourceY);
// set the current target pixel to the corrected pixel
buffer[x + (y * grid.Width)] = value;
}
}
}